Brake controlling structure



N- l. PERRY BRAKE CONTROLLING STRUCTURE June 19, 195 1 2 Sheets-Sheet, 1

Filed Aug. 17, 1945 I w WWW 1 R m w. N NM \NNW iR. m mm N b I. 2 IVN \N MN H 4. \M .5 RN \Q T m .1: N\ .d N W\ W. \wm. Y. \vr. H R g i s a 5 k MN m Q June 19, 1951 N. l. PERRY BRAKE CONTROLLING STRUCTURE 2 Sheets-Sheet 2 Filed Aug. 17, 1945 7 1 .Q i}. w, H W m 5 i1 l\N| N l M E F. T551 I, m? MN. z N NM INN n. a. 1 M1 NY M m N \M N \k. l N f Q W .w 5 I, \J QM? 7g j G, N wml NH, v \N MW Patented June 19, 1951 UNITED STATES PATENT OFFICE BRAKE CONTROLLING STRUCTURE Nelson I. Perry, Chicago, Ill.

Application August 17, 1945, Serial No. 610,935

The present invention relates to a brake controlling structure and more particularly to quick acting means for taking up slack in hydraulic brake systems used onv automotive vehicles.

Hydraulic brake systems for automotive vehicles comprise a closed system through which liquid is forced, by a brakelever or pedal, to apply the brakes. Due to wear of the brake shoes, and sometimes to a leak in the ssytem, the amount of pedal or lever travel, to apply stopping or holding pressure to the brakes, increases so that sometimes when the shoes are excessively worn, or a leak occurs, the brakes will not hold with the pedal orlever. at the limit of swing in brake applying direction.

An object of the present invention is to pro- -vide quick-acting slack takeup means for hydraulic brake systems.

Another object of the present invention is to provide in a hydraulic brake system means efiective on slight initial movement of the brake pedal of given amplitude for moving the brake shoes against the brake drums immediately prior to the application of braking pressure to the systesaid means including compensating means to move the shoes against the drums regardless of the worn condition of the shoes, for a given amplitude of movement of the brake pedal.

A further object of the present invention is to provide, in a hydraulic brake system for automotive vehicles, compensating means for slack takeup effective to move the hydraulic fluid in a system a distance sufficient to take up slack of the brake shoes regardless of the worn condition thereof without requiring a corresponding variation of pedal or lever movement.

Generally speaking the present invention contemplates a hydraulic braking system'in which a reservoir for'excess liquid is in communicationmoved in brake applying direction, which arm is connected to the piston of the second cylinder. The arm has a cam surface or profile engaged by the pedal on initiation of its movement in brake applying direction to swing the arm quickly away from its normal at-rest position. 'This quick movement of the arm through its connection to 9 Claims. (Cl. 6054.6)

the second piston imparts a quick kick to the second piston which is sufiicient to move liquid in the system from the second cylinder into the first cylinder and then into the line to move the brake shoes against the'brake drums of the vehicle, and thus take up the slack prior to the time the piston in the first cylinder becomes efiective to apply pressure to liquid in the cylinder. The connection between the arm or bar to the second piston includes an elastic member, so that for a given amplitude of swing of the barvaria tions in the travel of the second piston may take place, as the amount of travel of the second piston is directly proportional to the amount of wearof the liners of the brake shoes.

'The above, other and further objects of the present invention will be apparent from the fol: lowing description and accompanying drawings.

An embodiment of the present invention is illustrated in accompanying drawings, and the views thereof are as follows:

Figure 1 is the side elevational view of a brake mechanism of the present invention, showing certain parts in section and other parts in elevation, illustrating in full lines the relationships of the parts when the brakes are off, and in dotted lines the positions of certain parts for closing the port between the reservoir and the first or master cylinder, on initiation of pedal or dicated at It with a portion of a floorboardat l I. A bracket I2 is suitably secured to the under surface of the floor board Iii, and has pivotedto it at l3 a brake pedal indicated generally as A. The pedal A includes a shank I4, a tail l5 and a pusher 15, to the end of which is secured the usual foot plate, not shown, for the operators foot. At the junction of the" shank l4 and the pusher IS, a roller I1 is pivoted on an axle l8. Pivoted at l9 above the arc of travel of the pusher portion It, to the underface of the floor foot board II, is a pendulous or dangling arm or bar B. The arm has three cam surfaces or profiles lying in the path of movement of the roller H, and engageable successively by the roller as the pedal is moved in brake-applying direction. Profile 25 adjacent the pivot of the arm is straight, then the arm has a portion 2| with a cam profile 22 inclined towards the path of roller movement. The balance of the arm is constructed so that its profile, the third, is arcuate, struck on an arc the center of which is the axis of the pivot l3. The arm B is so pivoted that its straight or first profile of section 28 is tangential to the roller and bears against the roller when brakes are off.

A master cylinder 24 has a piston 25 slidable in it. One end of the cylinder is closed, through which end passes a pipe 25 which conveys liquid from the cylinder to the brake system of the vehicle. A connecting rod 21 is pivoted at one end at 28, to the tail l of the pedal A, and at its other end is pivoted at 29 to a wrist pin in the piston 25. Above the master cylinder '24 is a reservoir 39 for containing a supply of liquid. There is-a filler opening normally closed by a cap 3|. For providing communication between the interior of the reservoir 36 and the cylinder 24 there is a port 32. It will be noted that the port 3-2 is disposed near the head end of the piston 25 when the same is at rest with thebrakes in off position.

Pivoted, intermediate its ends, at l3, the pedal pivot, is a lever 33 which is adapted to rock on the pivot. Formed as a part of the arm or bar B is a lug 34. A link 35 is pivoted at one endof the lug 34 at 36. A coiled spring 31 has one end connected to other end of the link 35 and its other end connected to amend of link 38 which latter is pivoted at its other end at 39' to one, or the upper, end of the lever 33. Among other things the spring 3? functions to holdthe bar or arm B against the roller Disposed below the master cylinder 24 is a secondary cylinder 40 having a piston 4| slidable in it. A connecting rod is pivoted at one end 43 to the lower end of the lever 33 and at its other end is pivoted at 44 to a wrist pin in the piston 4|. A port 4-5 is provided afiording communication between the master cylinder 24 and the secondary cylinder 43.

A spring 46 is fastened at one end to a pin 41 in the vehicle structure, andat its other end is hooked at 48 to the shank of the pedal A, and

functions to maintain the pedal in its off, or

full-line position of Figure 1.

Operation When the brakes are oil, the brake shoes are held against stops by springs, in well known manner. With the brakes off the hydraulic system is filled with liquid by reason of the supply in the reservoir 33. With the brakes off, the pressure of the liquid in the system. is counterbalanced by the strength of the springs which hold the shoes'in oif or retracted position, so that initiation of pedal movement will overcome the resistance of the brake shoe springs to enable the system to move the shoes against the brake drums immediately prior to the time braking pressure is applied to the liquid in the system by the piston 25.

The slack referred to in this invention is that due to the normal withdrawn position of thebrake shoes when the brakes are oif. Vfnen the: shoes have new linings, this slack is very slight. As the linings become worn the slack increases. In other words, the slack contemplated by this invention is that distance through which theshoes must be moved to contact the brake drums distance.

immediately prior to the application of braking pressure to the system. This slack may be little or it may be much and is a function of the worn conditions of the linings of the brake shoes;

Referring to Figure 1, the full-line position of the parts denote the positions thereof when the brakes are off. To apply the brakes, the operator gives the brake lever a push. Initial movement of the pedal is that from the full line to the dotted line position of Figure 1. This is the first stage of brake movement, and during this movement the roller l1 rolls along the first or tangential cam profile of the arm B. Movement of'the pedal during the first stage of operation does not move the arm or bar B, but does move the piston in the master cylinder 24 a slight The distance indicated by dotted lines in Figure 1, which distance is sufiicient to close the port 32 between the reservoir and the cylinder 25. The second stage of pedal movement is that WhiCh'OCClllS when the roller engages the cam pro-file 22 ofythe bar B. As the roller I! encounters this profile 22, :the bar is swungquickly'to the left, or to the dotted line position of 'Figureu2. This-quick or sharp swing of the bar tensions the spring 3! and exerts pull on the links and 38, whereupon the arm 33'is rocked counterclockwise. Such movement of the bar B, being a quick one, will move'the piston 4| quickly to the right which movement drives some of the liquid there is in the secondary cylinder up through the port into the cylinder 24 and, because there-is no escape from the cylinder, which is completely filled, this liquid will be moved in the system through the pipe 26-taking up any slack there may be between the brake shoes and the drums, thus moving the shoes against the drums ready for the-application of braking pressure. Because of the quick movement of the bar B to the'left, the piston 4| will be operated ahead of the piston 25, which is movable by its connection to the pedal A. Thus the piston 5| imparts an impulse or kick to the liquid in the system, moving it a greater amount than it is moved by the piston 25, to thus add to the line a sufiicient amount of liquid to take up the slack, that is to move the brake shoes against the drums.

Under the impulseimparted to it by the movement of the bar B and the tension of the spring 31,-the piston 4| will be moved to the right until it is stopped by the opposition offered by the liquid in the system, which occurs when the shoes are moved against the drums. Piston 4| then stops, somewhere within the length of the cylinder 40 between the full line head of the piston and the right hand end of the cylinder. As before stated, this piston movement would be slight if the brake shoe linings are new or just adjusted and would be greater as the linings wear. As soon as movement of the piston 4| is stopped by the resistance offered by the liquid when the shoes are moved against the drums, further swing of the lever 33 will stop. The fact that the spring 3'! is interposed in the connection between the arm B and lever 33 makes it possible for'the arm to move to its limit of travel, irrespective of the fact-that the piston 4| is moving or is at rest.

The parts are so arranged that by the time the piston 4| has been moved to fill the system to move the brake shoes against the'drums, the piston 25 Within the master cylinder will have moved to the dotted line position of Figure 2 and thus close the port'to the cylinder 40. Such port closure, of course, stops further progress of the piston 4|. Thereafter, continued pedal movement through the third stage, which is that stage represented by engagement of the roller H with the arcuate profile 23 of the arm B,applies pressure to the entrapped liquid to thus press the brake shoes'against thebrake drums with suflicient force to 'efi'ect the braking action desired.

It must be kept in'mind that during the second stage of the pedal movement, that is while the roller I1 is against profile 22 of the arm or bar B, the swing of the arm B to the left may be such as to cause the piston 4| to move to the right far enough to move the shoes against the drums before the roller passes over the peak between the profiles 22 and 23. As before stated,

when this takes place, further movement of the piston 4| would stop. If there were a rigid connection between the arm or bar B and the lever 33, stopping of the piston 4| before the roller passes over the peakbetween the profiles 22 and 23'of' the arm or bar B, would prevent further movement of the armor bar to the left thus preventing actuating of the piston 25 in :the master cylinder '24 to apply pressure to the entrapped liquid and then to the brake shoes.

It will be noted that by the three stage operation of the pedal, as described, the initial or first stage movement closes the port between the reservoir and the master cylinder 24. The second stage movement causes operation of the piston 4| to add excess liquid to the system to move the brakes against the drums; thus'taiiing up slack. This movement of the brake shoes depends on the worn condition of the linings, but the present construction makes it possible for the piston 4| to move far enough to take up the slack regardless of the worn conditions of the linings, by a very small amplitude of movement of the pedal. "The amplitude of movement of the pedal to take up slack isfixed while the amplitude of movement of the piston 4| is variable. The spring 31 and the connection between the arm B and the piston 4| makes relative move ment of the bar andthe piston an accomplished fact, and compensates for the difference in relative movement of these two membersof the apparatus.

It will be observed that the present invention operates sequentially through at least three stages. The first stage of the pedal operation closes the port between the reservoir and the master cylinder. Second stage of pedal movement injects liquid from the secondary cylinder 40 into the system to move the brake shoes against r.

the drums, and the third stage of movement closes communications between the master cylinder and secondary cylinder and 'moves the piston 25 against the entrapped liquid to apply braking pressure to the shoes. Let it be understood that the pedal is given a push which is continuous up to the point where the desired pressure has been applied to the brakes. The three stages mentioned occur sequentially during such movement.

Whenthe operator removes his foot from the I pedal, the spring 46' returns the pedal to normal or inoperative position, releasing the brakes, the spring 31' returns the arm or bar B to its normal position, and at all times holds the bar or armB' against the roller As the pedal is returned to its normal or ofi position, the piston 25 is retracted, to open communication between the master cylinder and the secondary cylinder and also between the reservoir and the master Sll cylinder. As the arm or bar B is moved from its dotted line position of Figure 2 to the full line position, the piston 4| is retracted. The strength of the springs which withdraw the brake shoes from the brake drums, when pressure on the pedal is relieved, is sufiicient to cause a slight movement of the liquid against the head of the piston 4| to return it to'its normal position, if it has not already been moved to such position by the return of the arm B to its normal position.

The stroke of the piston 4| in the secondary cylinder 46 is variable due to the fact that the amount of fluid to be projected into the system to take up slack depends onthe worn condition of the liners ofthe shoes of the brakes. This stroke will vary from minimum to maximum, the minimum being'of a slight distance ahead of the full line position of the cylinder as shown in the drawings, with the maximum adjacent the right hand end of the cylinder 40. The piston 4| may be stoppedshort by (1) new shoe liners, in which event there is substantially no slack in the system, hence very slight movement of fluid need be projected by said piston to move the shoes against the drums; (2) closing of the port between the primary cylinder 24 and the secondary cylinder 4i); (3) fluid pressure against it before port 45 is closed.

When the shoes are against the drums, the system is full of fluid with no means of escape whereupon the first or primary piston 25 acts against the fluid with pressure action to apply the brakes. I

In the event the shoes contact the drums before the port 45 is closed by piston25 then there would be the same pressure. against the piston 4 I, as there is against the piston 25. This pressure would, if no compensating means were provided,

stop the swing of the bar B before the roller passes over the peak'between the second and third profiles of the cam surface of the bar, thus stopping swing of the bar under such circumstances, which would prevent movement of the piston 25 to apply the brakes. The elastic memher or spring 31 in the connection between the bar and the secondary piston 4| serves as compensating means to enable movement of the .bar to its maximum limit of swing as the roller I1 passes over the peak between the profiles 22 and 23.

The bar B must swing to its'limitto permit the roller I! to ride over the peak between the second and third profiles, as the piston 25 is not movable in pressure applying direction until the roller I? is on the third profile 23 of the bar, hence compensating means must be provided.

The present invention has been described herein. more or less precisely as to details, yet it is to be understood that the invention is not to be limited thereby as changes may be made-in the arrangement and proportion of parts, and equivalents may be substituted, without departing from the spirit and scope of the invention. I claim as my invention: 1. An actuating mechanism for use with a fiuid system, a first cylinder, a piston movable in said cylinder, a reservoir in communication with said cylinder, 2. secpnd cylinder, a piston in said second cylinder, said cylinders havingported communication, a pedal lever connected to the first piston, a pendulous arm pivoted at one end adjacent the pedal, connections between said arm and the second piston, said arm having a cam surface or profile near its pivot which is steep, a roller on said lever in the path of said arm,

,springmeansinsaid: connections-normally holdns said; arm against, said roller; the engagement 'of saidroller with said-cam quickly swinging said comprising, a'cylinder, agpiston-movablein the cylinder, a pedal: connected to said-piston to move it, a reservoir in communicationwith said cylinder to maintain the system full of liquid, an arm pivoted at one end adjacent said pedal having an-abrupt cam surface near its pivot, a roller on the pedal to contact said'cam, a secondary lever rockable on the pedal pivot, a spring connection between said arm and one end --of said lever, a secondary cylinder in flow communication-with said first cylinder, a piston in said secondary cylinder, a connection between the secondary piston cylinder and the'other end of said lever, initial short movement of the pedal moving said first piston to close the port-between the first cylinder and reservoir, subsequent short movement of the pedal causing said roller to move the arm quickly away from its normal position thereby imparting quick driving force to said second piston to move liquid in said system to take up slack, and subsequent movement of the pedal closing the port between said first and second cylinders and'moving the liquid in the system'to apply the brakes.

3. A brake actuating mechanism for use with a hydraulic brake system for automotive vehicles'comprising, amaster cylinder, a secondary cylinder, a reservoirin flow communication with said master cylinder, pistons in said cylinders, a pedal lever connected to the piston of the master cylinder, a secondary lever connected to the piston of said secondary cylinder, an armpivotally engaged by said pedal lever to swing, a'spring connection between'said arm and said secondary lever, initial short movement of the pedal moving the master cylinder piston to close the port to the reservoir and continued pedal movement causing the swing of said arm to quickly move the piston of the'secondary cylinder to urge liquid through the system to take up slack, subsequent short movement of the master cylinder piston closing the port to the secondary cylinder and continued movement by the pedal of the piston in the master cylinder moving the liquid in the system to apply the brakes.

4. An actuating mechanism for use with a fluid system, comprising a-pivoted lever, a pendulous cam bar pivoted at its upper end and lying in the path of movement of said lever to be swung'about its pivot as the lever'ismove'd in a first direction, a first cylinder and piston, a second-cylinder-and piston, a connection between said lever and said first piston, and a connection between said pendulous bar and said second piston, said cam bar having a series of cam profiles or-surfaces thereon engageable successively by said lever as it is moved in said firstdirection, the second of said cam surfaces being such as to cause quick swing of said cam bar whensaid second surface is contacted by said lever, the quick swing of said cam bar moving said second piston 'quickly to provide a relativelygreat fluid movement in the system for a relative short travel of the lever.

5. An actuating mechanism for use with a fluid system, comprising, a pivoted lever, a pendulous cam bar pivoted at its upper endand lying in the path of movement of. said lever to be swung about itspivotas the lever is moved in a first direction, a first "cylinder and piston a-second cylinder. and piston, a-connection betweensaid lever and said first piston, a connection between said'cam'bar and said second piston, the cam bar having a cam profile thereon engageableby-said vlever'inits initialmovement-to swing: said bar in a known arc, the connection between said cam bar and said second piston beingoperatedby swing of the bar toadvancesaid secondpiston, said last means including an elastic member which when the cam bar has beenswung-to its.:limit by said lever will continue to move said second piston untilthe fluid in the systemrattainsa; limiting pressure.

6. An actuating mechanism for use "with :a fluid system, comprising, -a manually operable lever, .a cylinden apiston within said cylinder having a variable stroke working :against the train of liquid-in said system a pendulous bar havingafixed amplitudeof swing, said bar lying in the path of movement of said'lever to be swung thereby as the lever-is actuated inl'a'first direction,-agconnection betweensaid'barfiand said piston -:to move 'salidxpistonagainst .the train :of liquid when 'the bar -.is swung 'in one (direction. said connection including 'an *elastic member which: when the bar. is :swnng: imposes a :pushing force against said piston aregardless of'theithen position'of the. bar to:move it-an'dithe' liquid train until 'thepressure in' the: systemreaches a limiting-value.

,7. "An actuatingl'mechanism' for ,usewith a'fluid system, comprising, a manually operable'levena first, cylinder: and piston for imposingtpressureto apply the brakes, arsecondzcylinder andzpiston foradding liquid ito thezfirst cylinder to :rapidly force fluid into the system ahead of :said ifirst cylinder, .ea connection between said lever and said first :piston, a pendulous bar "supported in the pathof movementof-said lever and :adapted tobe swung by said-lever as ibis-moved in:a first direction, said bar having acamrsurface engageable-by said lever toiswingzsaid bar in one-direction iin-afixed arc, a :connection 'betwen said bar and said second piston tomove said piston-against the liquid in the system as said bar is swung, said connection including an elastic member efiectivle to continue movement of said second pistonuntil the pressure in said system reaches a limiting value.

8. An actuating mechanism for use-with a fluid system, comprising, a lever pivoted to-swing, a roller'pivoted thereto to travel in an arcuatepath as the lever isswung,-a dangling cam'barpivoted at one end and lyin insthepathof travelof said roller and having varyingcamsurfaces thereon.

engageable successively by said roller -as said lever is swung in agiven directiomthe 'firstcam surface engageablebysaidroller during thefirst stage of lever movements being tangent withsaid roller to prevent any movementof-said cam bar as the rollermoves through the first stage, said second cam surface being inclined =toward and across the arcuate path of travel of said =roller whereby said second stage of pedal-movement will swing the free end of saidacam barsharply away from said arcuate path-of roller-travel, the third camsurface being concentric with thepedal axis of swing when thecam member is'moved beyond thehsecond-stage whereby the thirdstage swing of the lever will not effect movement'of the cam bar, and means set in motion :by the rapid-swing of the camber by the second-stage operation :0! the ;;pedal to .inject fluid into the system to ready the system for pressure action of the lever when the lever is moved through the third stage.

9. A11 actuating mechanism for use with a fluid system, a primary cylinder in flow communication with the system, a piston in said cylinder, a secondary cylinder in flow communication with said first cylinder, a piston in said secondary cylinder having a variable stroke, a lever, a pendulous bar having a fixed amplitude of swing and movable by said lever when the same is moved in a first direction, and connections between said bar and the piston of the secondary cylinder including an elastic member, said elastic member permitting completion of swing of said bar in one direction by said lever in the event that movement of the piston of said secondary cylinder is stopped short of its maximum limit of stroke.

NELSON I. PERRY.

10 REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

